1. Field of the Invention
The present invention relates to cargo containers and, more particularly, to expansible containers.
2. Description of the Prior Art
Liquids are normally transported in bulk and, where the use of a pipe line is impractical, they are conveyed in vehicles, railcars, aircrafts, or ships fitted with rigid tanks. One of the major factors contributing to the expense of transporting liquids in bulk in such specially constructed tankers is that, once having delivered their loads, whether by sea, air, road, or rail, they must usually make the return trip empty.
Therefore, expansible cargo containers capable of carrying alternatively liquid cargo or solid cargo were developed. U.S. Pat. No. 3,570,705 issued on Mar. 16, 1971 to Kassravi discloses such a cargo container which comprises a rigid walled structure within which there is provided a movable platform. A flexible corrugated sleeve is sealingly connected along its periphery to the platform and to a fixed rigid floor wall of the container to form an expansible vessel. The rigid walls support the sleeve against internal pressure from the liquids provided in the vessel and protect it from external damaging influences.
Therefore, supplying liquid in the expansible vessel causes the platform to displace vertically upwards with the platform retaining a substantial horizontality as being supported by the level liquid. The upwards movement of the platform is limited by inwardly projecting brackets provided at the top of the rigid walled structure. When the expansible vessel is empty of liquids, the platform is in a retracted position within the walled structure. A solid cargo receiving box-like structure is thus formed.